An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13116 Search : far
Kepler problem
  پراسه‌ی ِ کپلر   
parâse-ye Kepler

Fr.: problème de Kepler   

1) Given the trajectory of a particle moving in a → central force field, determine the law governing the central force.
2) Inversely, considering a central force -k/r2, determine the trajectory a particle moving in the field will take.

Kepler; → problem.

Kepler spacecraft
  تلسکوپ ِ فضایی ِ کپلر   
teleskop-e fazâyi-ye Kepler

Fr.: télescope spatial de Kepler   

A → NASA space telescope launched in March 2009 to discover Earth-size planets using the → transit method. The telescope has a diameter of 0.95 m and its only instrument is a → photometer that continuously monitors the brightness of over 145,000 → main sequence stars in a fixed field of view of 115 deg2 (about 12° diameter). The expected mission lifetime is 3.5 years extendible to at least 6 years.

In honor of Johannes → Kepler; → spacecraft.

Kepler's equation
  هموگش ِ کپلر   
hamugeš-e Kepler

Fr.: équation de Kepler   

An equation that enables the position of a body in an elliptical orbit to be calculated at any given time from its orbital elements. It relates the → mean anomaly of the body to its → eccentric anomaly.

Keplerian, adj. of → Kepler; → equation.

Kepler's first law
  قانون ِ نخست ِ کپلر   
qânun-e naxost-e Kepler (#)

Fr.: première loi de Kepler   

Planets move in elliptical paths, with the Sun at one focus of the ellipse (year 1609).

Kepler; → first; → law.

Kepler's laws
  قانون‌های ِ کپلر   
qânunhâ-ye Kepler (#)

Fr.: lois de Kepler   

1) The planets move about the Sun in ellipses, at one focus of which the Sun is situated.
2) The → radius vector joining each planet with the Sun describes equal areas in equal times.
3) The ratio of the square of the planet's period of revolution to the cube of the planet's mean distance from the Sun is the same for all planets.

Kepler; → law.

Kepler's second law
  قانون ِ دوم ِ کپلر   
qânun-e dovom-e Kepler (#)

Fr.: deuxième loi de Kepler   

A line joining a planet to the Sun sweeps out equal areas in equal intervals of time (year 1609).

Kepler; → second; → law.

Kepler's star
  ستاره‌ی ِ کپلر   
setâre-ye Kepler (#)

Fr.: étoile de Kepler   

A → supernova in → Ophiuchus, first observed on 1604 October 9, and described by Johannes Kepler in his book De stella nova (1606). It reached a maximum → apparent magnitude of -3 in late October. The star remained visible for almost a year. The → light curve is that of a → Type Ia supernova. The → supernova remnant consists of a few filaments and brighter knots at a distance of about 30,000 → light-years. It is the radio source 3C 358. Also known as SN 1604 and Kepler's supernova.

Kepler; → star.

Kepler's third law
  قانون ِ سوم ِ کپلر   
qânun-e sevom-e Kepler (#)

Fr.: troisième loi de Kepler   

The ratio between the square of a planet's → orbital period (P) to the cube of the mean distance from the Sun (a) is the same for all planets: P2a3 (year 1618). More accurately, P2 = (4π2a3) / [G(M1 + M2)], where M1 and M2 are the masses of the two orbiting objects in → solar masses and G is the → gravitational constant. In our solar system M1 = 1. The → semi-major axis size (a is expressed in → astronomical units and the period (P) is measured in years.

Kepler; → third; → law.

Keplerian
  کپلری   
Kepleri

Fr.: keplerien   

Of or pertaining to Johannes Kepler or to his works or discoveries.

From → Kepler + -ian a suffix forming adjectives.

Keplerian angular velocity
  تندای ِ زاویه‌ای ِ کپلری   
tondâ-ye zâviye-yi-ye Kepleri

Fr.: vitesse angulaire keplérienne   

The angular velocity of a point in a circular orbit around a central mass. It is given by: ΩK = (GM/r3)1/2, where G is the → gravitational constant, M is the mass of the gravitating object, and r is the radius of the orbit of the point around the object.

Keplerian; → angular; → velocity.

Keplerian disk
  گرده‌ی ِ کپلری، دیسک ِ ~   
gerde-ye Kepleri, disk-e ~

Fr.: disque keplérien   

A circumstellar disk (such as an → accretion disk or a → protoplanetary disk) in which the → angular velocity at each radius is equal to the angular velocity of a circular → Keplerian orbit at the same radius. The main characteristic of the Keplerian disk is that → orbital velocity varies as r-1/2. This means that an object on an orbit closer to the central mass turns more rapidly than that on a farther orbit. This velocity difference is at the origin of internal friction or kinematic viscous forces between disk particles, which heats up the material.

Keplerian; → disk.

Keplerian orbit
  مدار ِ کپلری   
madâr-e Kepleri (#)

Fr.: orbit keplérienne   

The orbit of a spherical object of a finite mass around another spherical object, also of finite mass, governed by their mutual → gravitational forces only.

Keplerian; → orbit.

Keplerian orbital velocity
  تندای ِ مدار ِ کپلری   
tondâ-ye madâr-e Kepleri

Fr.: vitesse d'orbite képlérienne   

The velocity of an object orbiting another object according to → Kepler's laws.

Keplerian; → orbital; → velocity.

Keplerian rotation curve
  خم ِ چرخش ِ کپلری   
xam-e carxeš-e Kepleri (#)

Fr.: courbe de rotation keplérienne   

A → rotation curve in which the speed of the orbiting body is inversely proportional to the → square root of its distance from the mass concentrated at the center of the system.

Keplerian; → rotation; → curve.

Keplerian shear
  کرن ِ کپلری   
karn-e Kepleri

Fr.: cisaillement keplerien   

Shearing motion of an ensemble of particles, each on a nearly circular, → Keplerian orbit. → Orbital velocity decreases as orbital radius increases, yielding shear. Viscous drag on such shear, due to ring-particle collisions, plays a key role in ring processes (Ellis et al., 2007, Planetary Ring Systems, Springer).

Keplerian; → shear.

Keplerian telescope
  دوربین ِ کپلر، تلسکوپ ِ ~   
durbin-e Kepler, teleskop-e ~ (#)

Fr.: télescope de Kepler   

A → refracting telescope which has simple → convex lenses for both → objective and → eyepiece. It suffers from → chromatic aberration, which can be reduced by increasing the → focal ratio. It was first devised by Kepler in 1615.

Keplerian; → telescope.

Kerberos
  کربروس   
Kerberos

Fr.: Kerberos   

The fourth → natural satellite of → Pluto discovered in 2011 using the → Hubble Space Telescope. Also called Pluto IV (P4). It has an estimated diameter of 14-44 km, which makes it the second smallest known moon of Pluto after → Styx. Kerberos revolves around Pluto in the region between → Nix and → Hydra at a distance of about 58,000 km and makes a complete orbit roughly every 32.1 days.

Named after the three-headed dog of Greek mythology.

kernel
  ا َستل   
astel

Fr.: noyau   

1) Chemistry: The remainder of an atom after the valence electrons have been removed.
2a) Math.: 1) The set of elements that a given function from one set to a second set maps into the identity of the second set.
2b) Let A be a linear transformation of the vector space U into the vector space V . The collection of all those vectors x in U such that Ax = 0 is called the kernel of A and is denoted by ker(A).
3) Computers: The set of functions that make up the operating system, the core that provides basic services for all other parts of the operating system. → core = maqzé (مغزه); → nucleus = hasté (هسته).

Kernel, from M.E. kirnel, from O.E. cyrnel, from P.Gmc. *kurnilo- (cf. M.H.G. kornel, M.Du. cornel), from *kernan- (root of corn "seed, grain"), akin to L. granium, + -el, diminutive suffix, variant of → -al.

Astel, from asté "kernel, fruit stone," variants hasté, ostoxân "bone," from Mid.Pers. astak "fruit stone, bone," ast "bone;" Av. ast- "bone;" cf. Skt. asthi- "bone;" Gk. osteon; L. os; Hittite hashtai-; PIE base *os- + Pers. diminutive suffix -el-al.

Kerr black hole
  سیه‌چال ِ کر   
siyah câl-e Kerr (#)

Fr.: trou noir de Kerr   

A → black hole that possesses only mass (not electric charge) and rotates about a central axis. It has an → ergosphere and a → stationary limit.

Named after the New Zealand mathematician Roy P. Kerr (1934-) who, in 1963, was the first to solve the → field equationss of Einstein's theory of → general relativity for a situation of this kind; → black hole.

Kerr-Newman black hole
  سیه‌چال ِ کر-نیومن   
siyah câl-e Kerr-Newman

Fr.: trou noir de Kerr-Newman   

A rotating charged black hole. Compare with the → Kerr black hole and the → Reissner-Nordstrom black hole.

Named after Roy P. Kerr and Ezra T. Newman (1929-) who in 1963 independently found this solution to Einstein's → field equations; → black; → hole.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>